In RC oscillators, the output frequency is determined by RC networks, in other words by resistors and capacitors.
An RC oscillator can for example be realised in that a capacitor is charged with a constant current, and the voltage resulting above the capacitor is compared to a threshold value or reference value. As soon as the voltage above the capacitor exceeds a predetermined threshold, the capacitor is rapidly discharged. Subsequently, renewed charging of the capacitor takes place. Thus it is primarily the capacitor's charging time constant which determines the clock pulse rate or frequency of the output signal of the arrangement. If necessary, the resulting sawtooth voltage can be converted to form a square-wave signal.